The present invention relates to monitoring of communications networks, and more particularly to communication monitoring in a mobile radio network.
In a mobile radio network data is transferred in the form of data packets or Packet Data Units (PDUs). The data transmitted includes both useful data and signaling data. Each mobile radio subscriber is allocated to a radio access entity that can exchange data with the subscriber via radio. The allocation may change with the movement of the subscriber. Each radio access entity is connected to a serving switching entity via a first link. Each serving switching entity exchanges data between plural radio access entities allocated to it or with a higher instance to which plural serving switching entities are allocated. Each serving switching entity is connected to a subscriber data base entity via a second link. The subscriber data base entity contains subscriber-oriented data of the subscriber allocated to it. The data exchanged between one radio access entity and its serving switching entity is ciphered data. First and second ciphering parameters are used for ciphering the first link. The first ciphering parameter is provided by the subscriber data base entity. The second ciphering parameter is recovered dynamically from the data exchange between such radio access entity and its serving switching entity.
Under a General Packet Radio Service (GPRS) standard the serving switching entity is a Serving GPRS Support Node (SGSN), the first link is a Gb interface, the second link is a Gr interface, the radio access entity is a Base Station Subsystem (BSS), and the subscriber data base entity is a Home Location Register (HLR).
Currently a stand-alone instrument, such as the Tektronix K1205 Protocol Tester manufactured by Tektronix Berlin GmbH, operates as a probe connected to a line, with deciphering taking place within a specific monitoring application of the instrument. All required Gb and Gr interfaces need to be connected directly to the instrument, which may provide up to sixteen (16) connections. No cooperation and especially no exchange of deciphering parameters with other instruments is possible. Any processing following deciphering, such as compiling statistics and call traces, is done directly within the instrument. However off-line processing, i.e., non-realtime processing, may be done on recorded files. Therefore, while the instrument may be used for monitoring the communication of selected links, generally it does not allow any real-time monitoring of an SGSN or of a complete mobile radio network.
Even if several instruments are used, they are not suited for cooperation with other instruments. If the instrument were expanded to a random number of connections, this only allows monitoring at fixed position, such as at an SGSN. If the data from individual instruments were collected, especially in a ciphered form for lack of ciphering parameters, and were forwarded to some central processing location, this no longer allows for realtime monitoring. Monitoring becomes virtually impossible when a mobile radio subscriber moves from the service area of a first SGSN into the service area of a second SGSN. In this case to get the correct deciphering parameters all the connections and also the inter-SGSN connections need to be monitored.
What is desired is an improved monitoring instrument that allows the monitoring of a complete mobile radio network or any portion thereof in realtime.